The purpose of this study is to determine whether endocrine testing in acute period correlates with neurologic outcome, and predicts late endocrine sequelae of head injury. Head-injured patients will be monitored for cortisol, thyroid function, prolactin, and water conservation. At 3 to 4 days after injury, the nocturnal TSH surge and response to TRH will be measured. Endocrine testing will be repeated at three months, one and two years after injury. Obvious deficiency will be treated.